The effect of Cl, Br, and F on high-temperature corrosion of heat-transfer alloys

Funding Information: This work was conducted within the Academy of Finland project “Initiation and propagation of high-temperature corrosion reactions in complex oxygen-containing environments” (Decision no. 348963). This work was partly supported by the project Clean and efficient utilization of demanding fuels (CLUE 2 ), with support from the industrial partners: ANDRITZ Oy, Valmet Technologies Oy, UPM-Kymmene Oyj, Metsä Fibre Oy, and International Paper Inc., as part of the activities of the Åbo Akademi University Johan Gadolin Process Chemistry Centre. Publisher Copyright: © 2023 The Author(s)The impact of small alkali halide additions on the melting behavior and corrosivity of a synthetic sulfate deposit at 500, 550, and 600 °C was investigated. Three differently alloyed commercial heat-transfer materials; low-alloyed 10CrMo9-10, stainless AISI 347, and high-alloyed Sanicro 28, were studied. The samples were exposed for 168 h in a tube furnace to a K2SO4 + Na2SO4 mixture containing 0.85 mol% KCl, KBr, or KF. The extent of material degradation was determined by weight loss measurements, while the morphology, thickness, and composition of the formed oxide scale were characterized with SEM-EDS. Additionally, the melting behavior of the mixtures was studied with TG-DTA. It could be concluded that already small amounts of reactive alkali halides in an otherwise inert K2SO4 + Na2SO4 mixture change significantly the corrosion and melting behavior of the mixture.Peer reviewe